Variable Angle Connection Assembly

ABSTRACT

In a preferred embodiment, the present invention provides a connection assembly that can be used to securely connect a spinal implant to a bone anchor. In particular, the present invention preferably provides a variable angle connection assembly that is able to securely connect the spinal implant to the anchors even when there is a variance in the angle and position of the anchors with respect to the spinal implant. Furthermore, in a preferred embodiment, the present invention provides a connection assembly that will not inadvertently lock the components of the connection assembly preventing the relative movement of the components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patent application Ser. No. 13/277,518 which is a continuation of U.S. patent application Ser. No. 12/343,027 filed on Dec. 23, 2008, which is incorporated by reference in its entirety herein.

FIELD OF THE INVENTION

The present invention relates generally to a connection assembly, and more particularly, to a variable angle spinal implant connection assembly.

BACKGROUND OF THE INVENTION

Spinal deformities, spinal injuries, and other spinal conditions may be treated with the use of spinal implants. Spinal implants are designed to support the spine and properly position the components of the spine. One such spinal implant includes an elongated rod and a plurality of bone anchors. The elongated rod is positioned to extend along one of more of the components of the spine and the bone anchors are attached to the spinal components at one end and secured to the elongated rod at the other end.

However, due to the anatomical structure of the patient, the spinal condition being treated, and, in some cases, surgeon preference, the bone anchors may be required to be positioned at various angles and distances from the elongated rod. As a result, it can be difficult to obtain a secure connection between the elongated rod and the bone anchors.

As such, there exists a need for a connection assembly that is able to securely connect an elongated rod to bone anchors despite a variance in the angle and position of the bone anchors with respect to the rod.

SUMMARY OF THE INVENTION

In a preferred embodiment, the present invention provides a connection assembly that can be used to securely connect a spinal implant to a bone anchor. In particular, the present invention preferably provides a variable angle connection assembly that is able to securely connect the spinal implant to the anchors even when there is a variance in the angle and position of the anchors with respect to the spinal implant. Furthermore, in a preferred embodiment, the present invention provides a connection assembly that will not inadvertently lock the components of the connection assembly preventing the relative movement of the components.

In a preferred embodiment, the connection assembly comprises a housing member that has an aperture for receiving a portion of a spinal implant, an opening for receiving a securing member for securing the spinal implant and a channel for receiving a receiving member. The receiving member preferably has an aperture for receiving a portion of an anchor, a rim portion having at least one ridge, and a lumen. In addition, in a preferred embodiment, the receiving member is configured and dimensioned to be received in the channel of the housing member so that the receiving member is rotatably and translatably connected to the housing member. An interference member is preferably received in the lumen of the receiving member and is translatable in the lumen. In a preferred embodiment, an end of the interference member has an anchor contacting surface for locking the anchor in place.

In a preferred embodiment, the connection assembly further comprises an annular member that is positioned over the receiving member and received in the channel of the housing member. Preferably, a face of the annular member has at least one ridge and the at least one ridge on the rim portion of the receiving member faces the at least one ridge on the second face of the annular member. In a preferred embodiment, the ridges are configured and dimensioned to engage with each other to lock rotational movement of the housing member and the receiving member.

Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred or exemplary embodiments of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a connection assembly;

FIG. 2 is an exploded perspective view of the connection assembly shown in FIG. 1;

FIG. 3 is an elevated side view of the connection assembly shown in FIG. 1;

FIG. 4 is a cross-sectional view of the connection assembly shown in FIG. 1 in the direction of arrows A-A;

FIG. 5 is a cross-sectional view of the connection assembly shown in FIG. 1 in the direction of arrows B-B; and

FIG. 6 is a cross-sectional view of another embodiment of a connection assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

With reference to FIGS. 1-4, a preferred embodiment of a connection assembly 10 is illustrated. The connection assembly 10 preferably includes a housing member 12 and a receiving member 14. The housing member 12 includes an elongated aperture 16 at a first end for receiving at least a portion of a spinal implant 20, such as a spinal rod, and the receiving member 14 includes an aperture 22 at a first end for receiving at least a portion of an anchor 24, such as a bone screw. One of ordinary skill in the art would recognize that although only a bone screw is shown, the aperture 22 of the receiving member 14 is capable of receiving any number of anchors including, but not limited to, other orthopedic screws, hooks, bolts, or other similar bone anchoring devices. The housing member 12 and the receiving member 14 are preferably rotatably connected to each other. The rotatable connection can be of any suitable design, including a threaded connection, a snap-fit, or a captured connection.

In a preferred embodiment, the housing member 12 also includes a second aperture 26 at the first end for receiving a securing member 28. The second aperture 26 extends from an outer surface of the housing member 12 toward the elongated aperture 16. In a preferred embodiment, the second aperture 26 is in fluid communication with the elongated aperture 16. At least a portion of the second aperture 26 is preferably threaded to receive the securing member 28, but the second aperture 26 can also be non-threaded.

The securing member 28 is preferably a threaded set screw, as best seen in FIG. 2, but can be any type of securing member including, but not limited to, a bolt, a pin, a shoe, an interference member, or a cam member. In a preferred embodiment, the securing member 28 is captured in the second aperture 26 preventing accidental disengagement of the securing member 28 from the housing member 12. The securing member 28 is captured in the second aperture 26 by including an overhanging portion 29 on the securing member 28 that abuts against the termination of the threading in the second aperture 26.

With continued reference to FIG. 2, the housing member 12 also includes, in a preferred embodiment, a channel 30 which extends from a second end of the housing member 12 toward the first end of the housing member 12. The channel 30 is in fluid communication with the elongated opening 16. Preferably, at least a portion of the channel 30 includes threading 31 interrupted by at least one groove 32 extending from the second end of housing 12 toward the first end of housing member 12. In a preferred embodiment, the at least one groove 32 extends towards the first end of the housing member only a predetermined amount and preferably includes an end face 33 that defines the end of the groove 32.

Referring to FIGS. 2 and 5, the receiving member 14, in a preferred embodiment, is generally cylindrical in shape with a generally tapered lumen 15. In another preferred embodiment, the lumen 15 may not be tapered and instead include a shoulder portion. The receiving member 14 further includes a radially outwardly extending rim portion 34 on a second end that has a plurality of ridges 36 preferably oriented toward the first end of the receiving member 14. In a preferred embodiment, the receiving member 14 also has a shoulder portion 38, spaced from the rim portion 34, on the second end of the receiving member 14. The receiving member 14 is configured and dimensioned to be received within the channel 30 of the housing member 12.

Turning back to FIGS. 1-5, the connection assembly 10 further includes, in a preferred embodiment, an interference member 40, a gear 42, a ring member 44, and a cap member 46. The interference member 40 has a generally polygonal shape that tapers from a second end to a first end. In a preferred embodiment, the first end of the interference member 40 has a saddle portion 48 that is configured and dimensioned to abut the anchor 24 and the second end of the interference portion 40 has a face 49 from which a cutout 50 extends towards the first end. The face 49 preferably is flat, but may also be arcuate and generally conforms to the shape of the spinal implant 20. In another preferred embodiment, the interference member 40 has a generally rectangular shape with a first end having a saddle portion that is configured and dimensioned to abut the anchor and a second end that flares outwardly and includes a face for abutting the spinal implant and a cutout. Although the cutout 50 is located near the second end of the interference portion 40, it is envisioned that the cutout 50 also be located near the first end of the interference portion 40. The interference portion 40 is configured and dimensioned to be received within the lumen 15 of the receiver member 14.

The gear 42, as best seen in FIG. 2, preferably is generally annular in shape and has a plurality of ridges 52 on one face and at least one projection 54 extending radially outwardly from the gear 42. In a preferred embodiment, the gear 42 is configured and dimensioned to fit over the shoulder portion 38 of the receiving member 14 and within channel 30 of the housing member 12. The gear 42 is preferably oriented so that the ridges 52 face the ridges 36 on the rim portion 34 of the receiving member 14 and the at least one projection 54 is received within the at least one groove 32 in the housing member 12.

In a preferred embodiment, the ring member 44 is generally annular in shape, has a first face and a second face, and is configured and dimensioned to fit over the receiving member 14 and abut against the shoulder portion 38, as best seen in FIGS. 4 and 5. Preferably, the ring member 44 also is configured and dimensioned to be received within the channel 30 of the housing member 12. In a preferred embodiment, the ring member 44 is made from titanium, but the ring member 44 can also be made from any biocompatible material including resilient polymers.

The cap member 46, in a preferred embodiment, is generally cylindrical in shape and tapers from a first end to a second end. The cap member includes an extension portion 56 near the first end of the cap member and a lumen 60. As best seen in FIGS. 2, 4 and 5, the extension portion 56 preferably is threaded along at least a portion thereof and includes a ramp portion 57. Although the extension portion 56 preferably includes threading, in another preferred embodiment, the extension portion may not be threaded. Preferably, the diameter of the extension portion 56 is smaller than the diameter of the portion of the cap member 46 immediately adjacent to the extension portion 56 creating a shoulder portion 58. In a preferred embodiment, the cap member 46 is configured and dimensioned so the extension portion 56 engages the threading 31 in the channel 30 of the housing member 12 and the shoulder portion 58 abuts the second end of the housing member 12. The lumen 60 of the cap member 46 is configured and dimensioned to receive the receiving member 14. In a preferred embodiment, the cap member 46 is captured in the channel 30 of the housing member 12 to prevent the cap member 46 from inadvertently unthreading from the housing member 12.

With reference to FIGS. 1 and 3-5, in a preferred arrangement of the elements of the connection assembly 10, the housing member 12 is rotatably connected to the receiving member 14. As mentioned above, the receiving member 14 is received within the channel 30 of the housing member 12. In a preferred embodiment, the second end of the receiving member 14 abuts a medial wall 13 located within the housing member 12 and the first end of the receiving member 14 extends beyond the second end of the housing member 12. Positioned within the lumen 15 of the receiving member 14 is the interference member 40.

In a preferred embodiment, also received within the channel 30 of the housing member 12 is the gear 42 which fits over the shoulder portion 38 of the receiving member 14. The at least one projection 54 on the gear 42 is received within the at least one groove 32 and preferably abuts the end face 33 of the groove 32. The end face 33 of the groove 32 is spaced from the medial wall 13 of the housing member 12 by a predetermined amount, so the gear 42, when placed in the channel 30, is spaced from the rim portion 34 of the receiving member 14 by a predetermined amount. Accordingly, the ridges 36 on the rim portion 34 are spaced from the ridges 52 on the gear 42. The purpose of this spacing is important and is explained further below.

In a preferred embodiment, the ring member 44 is also received within the channel 30 of the housing member 12 and also fits over the receiving member 14. However, the inner diameter of the ring member 44 is smaller than the shoulder portion 38 of the receiving member 14. As a result, at least a portion of the second face of the ring member 44 will abut the shoulder portion 38. Preferably, the remaining portion of the second face of the ring member 44 will contact the gear 42.

The cap member 46, in a preferred embodiment, is also received within the channel 30 of the housing member 12 and also fits over the receiving member 14. The threads on the threaded portion 56 engage with the threads 31 on the channel 30 to threadingly engage the threaded cap 46. Preferably, the threaded portion 56 is threaded into the channel 30 until the shoulder portion 58 contacts the second end of the housing member 12. In this position, the ramp portion 57 of the threaded portion 56 abuts the first face of the ring member 44.

The preferred arrangement of the elements, as discussed above, allow the housing member 12, the gear 42 and the cap member 46 to rotate with respect to the receiving member 14, the ring member 44, and the interference member 40. As the housing member 12 rotates, the gear 42 will also rotate because of the at least one projection 54 located in the at least one groove 32. Likewise, since the cap member 46 is threaded and preferably captured in the channel 30 of the housing member 12, the cap member 46 also rotates when the housing member 12 rotates. In contrast, the receiving member 14, although captured within the channel 30 of the housing member 12 by virtue of the cap member 46 and the rim portion 34, is capable of rotating as well as translating within the channel 30. Accordingly, the receiving member 14 does not rotate when the housing member 12 rotates. Similarly, the ring member 44, although captured within the channel 30 of the housing member 12 by virtue of the shoulder portion 38 of the receiving member 14 and the ramp portion 57 of the cap member 46, is capable of rotating within channel 30. Consequently, the ring member 44 does not rotate when the housing member 12 rotates.

A preferred connection of the spinal implant 20 to the anchor 24 through the connection assembly 10 is best depicted in FIGS. 1, 3 and 4. In an exemplary use, the anchor 24 is implanted into a component of the spinal column, such as a vertebral body in the spinal column. Preferably, the aperture 22 of the receiving member 14 of the connection assembly 10 receives the anchor 24. The aperture 22 is configured and dimensioned to receive any portion of the anchor 24 allowing the connection assembly 10 to be placed anywhere along the length of the anchor 24. Accordingly, the connection assembly 10 can be translated along the anchor 24 until the desired position is achieved.

In an exemplary use, the spinal implant 20 is typically placed along at least a portion of the length of the spinal column in an orientation that is generally perpendicular to the anchor 24. Preferably, the spinal implant 20 is also received in the connection assembly 10, where the spinal implant 20 is received in the elongated opening 16 in the housing member 12. The elongated opening 16 is configured and dimensioned to receive any portion of the spinal implant 20 allowing the connection assembly 10 to be place anywhere along the length of the spinal implant 20.

Additionally, since the housing member 12 and the receiving member 14 are rotatably connected to each other, even if the anchor 24 and the spinal implant 20 are angularly offset, the connection member 10 can be oriented to a desired position to connect the spinal implant 20 and the anchor 24. Once the desired angular orientation and translational positioning of the connection assembly 10 with respect to the anchor 24 and the spinal implant 20 is achieved, the connection assembly 10 can be locked, securing the anchor 24 and the spinal implant 20.

To lock the connection assembly 10, the securing member 28 is threaded into the second aperture 26 in the housing member 12 where it contacts and pushes the spinal implant 20 toward the anchor 24. The spinal implant 20 contacts the face 49 of the interference member 40 and pushes the interference member 40 towards the anchor 24. As the interference member 40 is pushed by the spinal implant 20 towards the anchor 24, the interference member 40, with the aid of the cutout 50, compresses in the lumen 15 of the receiving member 14, and continues towards the anchor 24, while the receiving member 14 remains stationary. The saddle portion 48 of the interference member 40 abuts the anchor 24, pushing the anchor 24 into a sidewall of the aperture 22 in the receiving member 14, locking the anchor 24 in place with respect to the connector assembly 10.

As the spinal implant 20 continues to move towards the anchor 24 and continues to push the interference member 40, the interference member 40 no longer being able to compress any further in the lumen 15, pushes against the walls of the lumen 15 and moves the receiving member 14. As the receiving member 14 moves, the shoulder portion 38 pushes against the second face of the ring member 44. Since the first face of the ring member 44 abuts the ramp portion 57 of the cap member 46, after a predetermined force is applied to the ring member 44 by the shoulder portion 38, the ring member 44 deflects or bends in the direction of the ramp portion 57. With the ring member 44 no longer blocking the shoulder portion 38, the receiving member 14 continues moving towards the anchor 24 until the ridges 36 on the rim portion 34 of the receiving member 14 engage the ridges 52 on the gear 42. With the ridges 36 and 52 engaged, the relative rotation of the housing member 12 and the receiving member 14 of the connection assembly 10 is locked. At this point, the spinal implant 20 is also locked in place between the threaded member 28 and the walls of the housing member 12 that define the elongated opening 16. With the spinal implant 20 locked in place, the relative rotation of the housing member 12 and the receiving member 14 locked, and the anchor 24 locked in place, the entire assembly is locked against movement. Adjustments to the entire assembly can be made by loosening the threaded member 28 and then re-tightening the threaded member 28 once the preferred positioning and orientation has be achieved.

It is important to note that because of the shoulder portion 38 abutting the ring member 44 and the at least one projection 54 of the gear 42 abutting the end face 33 of the at least one groove 32, prior to the bending or deflection of the ring member 44, the ridges 36 on the rim portion 34 of the receiving member 14 can not engage the ridges 52 on the gear 42. This arrangement of elements prevents any inadvertent engagement of the ridges 36, 52 thereby preventing any unintended rotational locking of the housing member 12 with respect to the receiving member 14.

Turning now to FIG. 6, a second preferred embodiment of a connection assembly 110 is shown. The connection assembly 110 preferably includes a housing member 112 and a receiving member 114. The housing member 112 includes an elongated aperture 116 at a first end for receiving at least a portion of a spinal implant 120 and the receiving member 114 includes an aperture 122 at a first end for receiving at least a portion of an anchor 124. The housing member 112 and the receiving member 114 are preferably rotatably connected to each other.

In a preferred embodiment, the housing member 112 also includes a second aperture 126 at the first end for receiving a securing member 128. The second aperture 126 extends from an outer surface of the housing member 112 toward the elongated aperture 116. In a preferred embodiment, the second aperture 126 is in fluid communication with the elongated aperture 116. At least a portion of the second aperture 126 is preferably threaded to receive the securing member 128. In a preferred embodiment, the securing member 128 is captured in the second aperture 126 preventing accidental disengagement of the securing member 128 from the housing member 112.

With continued reference to FIG. 6, the housing member 112 also includes, in a preferred embodiment, a channel 130 which extends from a second end of the housing member 112 toward the first end of the housing member 112. The channel 130 is in fluid communication with the elongated opening 116. Preferably, at least a portion of the channel 130 includes threading 131.

The receiving member 114, in a preferred embodiment, is generally cylindrical in shape with a cylindrical lumen 115 extending from a second end to the first end. Preferably, the cylindrical lumen is in fluid communication with the aperture 122. In a preferred embodiment, in the lumen 115 of the receiving member 114, a plurality of ridges 132 are present. The receiving member 114 is configured and dimensioned to be received within the channel 130 of the housing member 112 and includes threading 117 on an outer surface thereof to engage with the threading 131 in the channel 130. Since the receiving member 114 is threadingly received in the channel 130 of the housing member 112, the lateral position of the receiving member 114 with respect to the housing member 112 can be adjusted by rotating the receiving member 114. This allows for controlled lateral adjustment of the anchor 124 with respect to the spinal implant 120.

The connection assembly 110 further includes, in a preferred embodiment, an implant interference member 140 and an anchor interference member 142. The implant interference member 140 has a generally cylindrical shape and includes a channel 144 that extends from a first end towards a second end of the implant interference member 140. In a preferred embodiment, at least a portion of the channel 144 of the implant interference member 140 includes threading 146 to engage the anchor interference member 142. The implant interference member 140 also preferably includes at least one cutout portion 145, extending from the second end towards the first end, that separates at least a portion of the implant interference member 140 into sections. In a preferred embodiment, the implant interference member 140 also includes ridges 148 on an outer surface thereof. The implant interference member 140 is configured and dimensioned to be received in part within the lumen 115 of the receiving member 144 and in part within the channel 130 of the housing member 112.

The anchor interference member 142, in a preferred embodiment, also is generally cylindrical and includes threading 150 extending along at least a portion of the anchor interference member 142 from a second towards a first end. The anchor interference member 142 is configured and dimensioned to be received within the channel 144 of the implant interference member 144. In a preferred embodiment, the threading 150 of the anchor interference member 142 threadingly engages the threading 146 in the channel 144 of the implant interference member 140.

With continued reference to FIG. 6, to lock the connection assembly 110, the securing member 128 is threaded into the second aperture 126 in the housing member 112 where it contacts and pushes the spinal implant 120 toward the anchor 124. The spinal implant 120 contacts the implant interference member 140 and pushes the implant interference member 140 towards the anchor 124. As the implant interference member 140 is pushed by the spinal implant 120 towards the anchor 124, the anchor interference member 142, which is threadingly engaged with the implant interference member 140, also moves towards the anchor 124. The first end of the anchor interference member 142 abuts the anchor 124, pushing the anchor 124 into a sidewall of the aperture 122 in the receiving member 114, locking the anchor 124 in place with respect to the connector assembly 110.

As the spinal implant 120 continues to move towards the anchor 124 and continues to push the implant interference member 140, the implant interference member 140 abuts against a medial wall 152 in the receiving member 114 and is no longer able to translate in the lumen 115 of the receiving member 114. The continued movement of the spinal implant 120 toward the anchor 124 results in the implant interference member 140 splaying radially outwardly with the aid of the at least one cutout 145. The implant interference member 140 splays outwardly until until the ridges 148 on the puter surface of the implant interference member 140 engage the ridges 132 in the lumen 115 of the receiving member 114. With the ridges 132 and 148 engaged, the relative rotation of the housing member 112 and the receiving member 114 of the connection assembly 110 is locked. At this point, the spinal implant 120 is also locked in place between the threaded member 128 and the walls of the housing member 112 that define the elongated opening 116. With the spinal implant 120 locked in place, the relative rotation of the housing member 112 and the receiving member 114 locked, and the anchor 124 locked in place, the entire assembly is locked against movement. Adjustments to the entire assembly can be made by loosening the threaded member 128 and then re-tightening the threaded member 128 once the preferred positioning and orientation has be achieved.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims. 

What is claimed is:
 1. A connection assembly for connecting a spinal implant to an anchor, the connection assembly comprising: a housing member having a first end and a second end, the housing member having an aperture proximate the first end for receiving a portion of a spinal implant and a channel extending from the second end towards the first end, the channel is in fluid connection with the aperture and oriented generally transversely to the aperture; a receiving member having a first end and a second end, the receiving member having an aperture proximate the first end for receiving a portion of an anchor and a lumen extending from the second end towards the first end, the lumen is in fluid communication with the aperture and oriented generally transversely to the aperture, the second end of the receiving member is received in the channel so that the receiving member is rotatably and translatably connected to the housing member; a cap member having a lumen and an extension portion, wherein the channel of the housing member receives the extension portion of the cap member.
 2. The connection assembly of claim 1, the connection assembly further comprising: an annular member having a first face and a second face, the annular member positioned over the receiving member and received in the channel, wherein the receiving member has a rim portion having at least one ridge proximate the second end, wherein the second face of the annular member has at least one ridge, and wherein the at least one ridge on the rim portion faces the at least one ridge on the second face of the annular member.
 3. The connection assembly of claim 2, wherein the housing member has an opening proximate the first end for receiving a securing member.
 4. The connection assembly of claim 3 further comprising a spinal implant in the aperture of the housing member, an anchor in the aperture of the receiving member, and a securing member in the opening in the housing member, wherein the securing member presses the elongated spinal implant against the interference member and the housing member to lock the elongated spinal implant, the interference member, the receiving member, the annular member and the bone anchor with respect to each other.
 5. The connection assembly of claim 1, the connection assembly further comprising a ring member having a first face and a second face, wherein the receiving member has a shoulder portion, and wherein the ring member is positioned over the receiving member and received in the channel, the second face of the ring member contacts the shoulder portion.
 6. The connection assembly of claim 2, wherein the annular member has at least one projection and the channel has at least one groove for receiving the at least one projection.
 7. The connection assembly of claim 1, wherein the extension portion is threaded and at least a portion of the channel is threaded so that the cap member is threadingly received in the channel of the housing member.
 8. The connection assembly of claim 1, wherein the lumen is configured and dimensioned to receive the receiving member.
 9. The connection assembly of claim 1, wherein the interference member has a saddle portion at a first end and a cutout at the second end.
 10. A connection assembly for connecting a spinal implant to an anchor, the connection assembly comprising: a housing member having a first end and a second end, the housing member having an aperture proximate the first end for receiving a portion of a spinal implant and a channel extending from the second end towards the first end, the channel is in fluid connection with the aperture and oriented generally transversely to the aperture; a receiving member having a first end and a second end, the receiving member having an aperture proximate the first end for receiving a portion of an anchor, a shoulder portion proximate the second end, and a rim portion proximate the second end, the second end of the receiving member is received in the channel so that the receiving member is rotatably and translatably connected to the housing member; a ring member having a first face and a second face, the ring member positioned over the receiving member and received in the channel, the second face of the ring member contacting the shoulder portion; and a cap member having a lumen for receiving the receiving member and an extension portion, the extension portion of the cap member is received in the channel and contacts the first face of the ring member, wherein the channel includes at least one groove for receiving the at least one projection.
 11. The connection assembly of claim 10, further comprising: an interference member having a first end and a second end, the first end of the interference member having an anchor contacting surface, wherein the receiving member has a lumen extending from the second end towards the first end, the lumen is in fluid communication with the aperture and oriented generally transversely to the aperture, and wherein the interference member is translatably received in the lumen.
 12. The connection assembly of claim 11, wherein the interference member has a saddle portion at a first end and a cutout at the second end.
 13. The connection assembly of claim 10, further comprises an annular member having a first face and a second face, the annular member positioned over the receiving member and received in the channel.
 14. The connection assembly of claim 13, wherein the rim portion has at least one ridge, wherein the second face of the annular member has at least one ridge, and wherein the at least one ridge on the rim portion faces the at least one ridge on the second face of the annular member.
 15. The connection assembly of claim 10, wherein the housing member has an opening proximate the first end for receiving a securing member.
 16. The connection assembly of claim 15, further comprising a spinal implant in the aperture of the housing member, a securing member in the opening, and an anchor in the aperture of the receiving member, wherein the spinal implant is an elongate spinal rod, wherein the securing member is a set screw, and wherein the anchor is a bone screw.
 17. The connection assembly of claim 11, wherein the extension portion is threaded and at least a portion of the channel is threaded so that the cap member is threadingly received in the channel of the housing member.
 18. A connection assembly for connecting a spinal implant to an anchor, the connection assembly comprising: a housing member having a first end and a second end, the housing member having an aperture proximate the first end for receiving a portion of a spinal implant, an opening proximate the first end for receiving a securing member, and a channel extending from the second end towards the first end, the channel is in fluid connection with the aperture and oriented generally transversely to the aperture; a receiving member having a first end and a second end, the receiving member having an aperture proximate the first end for receiving a portion of an anchor, a shoulder portion proximate the second end, a rim portion proximate the second end, and a lumen extending from the second end towards the first end, the lumen is in fluid communication with the aperture and oriented generally transversely to the aperture, the second end of the receiving member is received in the channel so that the receiving member is rotatably and translatably connected to the housing member; a cap member having a lumen for receiving the receiving member and an extension portion, the extension portion of the cap member is received in the channel and contacts the first face of the ring member. 